I only leave negative or 5 star feedback for those who really deserve it. Some sellers quickly and friendly answer all messages, pack everything well and ship the same or next day. All other sellers that were just "ok" (no answer, slow shipping, poorly packed but not damaged, slightly excessive shipping) can be glad that I don't bother to leave feedback, but they also don't get a positive feedback for an average job.
I'm rather surprised about the inflationary positive feedback and detailed rating most sellers have. I don't see how a seller who ships for free the same day has 5 stars and a seller that charges $9.97 per game and take several days to ship has 4.8 or 4.9.